From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45D71C433F5 for ; Thu, 26 May 2022 08:01:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A91028D0003; Thu, 26 May 2022 04:01:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A40438D0001; Thu, 26 May 2022 04:01:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 92D1A8D0003; Thu, 26 May 2022 04:01:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 8045C8D0001 for ; Thu, 26 May 2022 04:01:18 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 4CCE8204CE for ; Thu, 26 May 2022 08:01:18 +0000 (UTC) X-FDA: 79507149036.24.7FC46A2 Received: from mail-pj1-f42.google.com (mail-pj1-f42.google.com [209.85.216.42]) by imf30.hostedemail.com (Postfix) with ESMTP id 6547380007 for ; Thu, 26 May 2022 08:00:47 +0000 (UTC) Received: by mail-pj1-f42.google.com with SMTP id ge11so1155916pjb.0 for ; Thu, 26 May 2022 01:01:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=cPBo1/z66AxJUif/4bPiA1dLl6Egi0hfAP6GvoU1sV0=; b=6NDxIR+6uUjB7dCwGwcfqdek2+lKlTwfSd4MrrZtOi2+ClUTwfkElbtFD8Eis/0Y0K 4yzinANtUEfNW6aZ5PgGrCpUDiKmjpMuxDDBuBoNx8J+Ltp630gvBrHk6vVEHJODIJqT H2C/fYRd3/28omWbOUzOTnBOAqisf5q8P8Y/ff38fXBVnD4uQD/pu+t/NpvE0qOca6fs 87xzlWTEWFqJeIeqSbDGWHVKqe55zklRpv5o1vKs3+qVQ1s0PyaJIInHW2j4r6Nl7LIZ AqFFcCAYF6n1O5RWdxeTBQYS3DQrroQd6sGgvQCswwxKGSPNyTvhFHu6XWONMl6wHyJC IhDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=cPBo1/z66AxJUif/4bPiA1dLl6Egi0hfAP6GvoU1sV0=; b=c2xlMQBBFlBnjXlB0NKpeJLgvVUPYAB/ORIkk/4mviBSTHN57V8IhAEjCuFmCLWORm hALivCZmGAF+sbEIw4xdg7Rk0EEOsZctbx+SZiStJHiXaLUOxKOZhKIrIpkoh8DugVaZ XhNvyckLwfamzQC0Pqx923VduRxDKCw0dAajLgq5aFWYZVja4Gpj8oasc/M2H/+0hWs1 4Tv0fX2yxehERYvSeZah1UwT1Rsoh/lZ6qMo7+UKeO+WhI5PIAzNMrlUR0MI2PSs4V2Y 2C4/izgcExGgCvYxgQblpnQiDxinbvAd9ASfvArL5+bhmye0Pp37FAUueFLaxw1ByDEn yRoA== X-Gm-Message-State: AOAM532b+qclLKuviy8qm70m2VwuPmbQScEZwqYBojFKC4kWiv7HiVdq 1VW+XuaCnTm8PS9WNJVUztQ+nw== X-Google-Smtp-Source: ABdhPJwDoYXHfQff5yRn4D7OgwdsNB7fZai9C6375HvH4oaizoEl5HaKAQtrJ59CkBsSddya7lY9xw== X-Received: by 2002:a17:903:240b:b0:14b:1100:aebc with SMTP id e11-20020a170903240b00b0014b1100aebcmr37188416plo.133.1653552074176; Thu, 26 May 2022 01:01:14 -0700 (PDT) Received: from localhost ([139.177.225.238]) by smtp.gmail.com with ESMTPSA id e14-20020a170903240e00b0015e8d4eb1fasm806650plo.68.2022.05.26.01.01.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 May 2022 01:01:13 -0700 (PDT) Date: Thu, 26 May 2022 16:01:10 +0800 From: Muchun Song To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , stable@vger.kernel.org Subject: Re: [PATCH] hugetlb: fix huge_pmd_unshare address update Message-ID: References: <20220524205003.126184-1-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220524205003.126184-1-mike.kravetz@oracle.com> X-Rspamd-Queue-Id: 6547380007 X-Stat-Signature: s9td36ymxt9d1y4ccqt6b9m4qpji1ab6 Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=6NDxIR+6; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf30.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.216.42 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1653552047-910227 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, May 24, 2022 at 01:50:03PM -0700, Mike Kravetz wrote: > The routine huge_pmd_unshare is passed a pointer to an address > associated with an area which may be unshared. If unshare is successful > this address is updated to 'optimize' callers iterating over huge page > addresses. For the optimization to work correctly, address should be > updated to the last huge page in the unmapped/unshared area. However, > in the common case where the passed address is PUD_SIZE aligned, the > address is incorrectly updated to the address of the preceding huge > page. That wastes CPU cycles as the unmapped/unshared range is scanned > twice. > > Cc: > Fixes: 39dde65c9940 ("shared page table for hugetlb page") > Signed-off-by: Mike Kravetz Acked-by: Muchun Song Thanks.